I think that may have been less about winning the case, and more about getting the word out that the 'test' Top Gear did was edited in a way that maximized humor vs. being 100% accurate.
The Top Gear review was essentially accurate, at least IMHO.
Tesla argued in court that it was unfair to mention the car's disappointing range on the test track because most people won't be driving on a test track. A strange argument, especially for a sports car. Note that they did not argue that the range number cited was wrong -- just that it might confuse potential buyers.
The judge ruled that: "no reasonable person watching the programme could understand that the performance on the track is capable of direct comparison with the performance, including the range, on the road"